Foulsham, London's great filth repository, is bursting at the seams. The walls that keep the muck in are buckling, rubbish is spilling over the top, back into the city that it came from. In the Iremonger family offices, Grandfather Umbitt Iremonger broods: in his misery and fury at the people of London, he has found a way of making everyday objects assume human shape, and turning real people into objects.

Abandoned in the depths of the Heaps, Lucy Pennant has been rescued by a terrifying creature, Binadit Iremonger - more animal than human. She is desperate and determined to find Clod. But unbeknownst to her, Clod has become a golden sovereign and is 'lost'. He is being passed as currency from hand to hand all around Foulsham, and yet everywhere people are searching for him, desperate to get hold of this dangerous Iremonger, who, it is believed, has the power to bring the mighty Umbitt down.

But all around the city, things, everyday things, are twitching into life...